Antislipping tile



HER-BERT 3K. DODGE, 0F EALISADES. NEW JERSEY. ASSXGNOR 'E0 NRTN' I A CUPvllPOlil/ALJEGN 0F TEASSACEUSETTS.

contrarier,

estraneo,

Application filed .april 29,

To @ZZ whom t may concern:

Be it known that l, ilmenau: l.. Dones, a citizen of the United States of America, residing at Palisades, in the county of 5ergen and State of New Jersey, have invented certain new and useful lmprovements in Antislipping Tiles, of which the following is a full, clear, and enact specification.

My invention relates to safety treads and more particularly to anti-slipping' tread blocks or tiles having a high surface coeflicient of friction and great resistivity to footwear.

Owing to the frequent accidents caused by persons slipping on stairways and public walks made of wood, brick, paving stone, concrete, etc., numerous attempts have been made, as by forming the treads with corrugated or discontinuous surfaces, to render such materials safe for pedestrians, but heretofore no tread has been found capable of retaining its anti-slipping characteristics and original form where exposed to the constant wear of pedestrian traffic.l

rl`he anti-slipping properties of the extremely hard abrasive materials have been recognized and flooring and paving construction experts have attempted to provide safety treads by incorporating such abrasives in artificial blocks or stones. For en ample, small amounts of'isolatednabrasive grains have been embedded 1n various substances, such as asphalt, rubber and other organic bodies which produce a lire hazard, or in lead or cements, such as magnesium oxychlorid or concrete. Such enveloping substances have little durability -or poor adhesion to the abrasive grains, hence where the body of the tread is exposed to wear, the grains are soon loosened from their settings and the utility of the tread impaired.

vTo overcome this objection, tread strips made of lead or cement containing abrasive are set in grooved metal frames, but the safety tread portion wears away and leaves the smooth iron of the frame exposed and thus endangers the pedestrian. Moreover, such treadl constructions require that the nose of a 'stair bemade of metal, which is smooth, whereas the stair edge should have the maximum anti-slipping characteristics. Similarly, abrasive grains have been cast in the tread portions of iron blocks, but these soon wear out and the tread blocks become smooth and slippery metal surfaces.

Specieation of Letters Patent.

Fatented May Eid, iii.

serial no. 231,417.

l have discovered, on the other hand, that a safety tread which will be permanently wear-resisting and safe for pedestrians may be made in the form of a tile of durable, anti-slipping, granular material constituting the major portion of the tread volume, and bonded together by a medium capable of uniting them integrally into a wear-resisting structure, as distinguished from a body in which isolated grains are embedded.

With these features in mind, one object of my invention is to provide a unitary tread block which in itself is tough, hard' and of high tensile strength, which resists footwear to a high degree and has along life of utility and which retains a rough friction surface under all conditions of normal pedestrian wear.

A further object of my invention is to utilize durable, granular abrasive materials and make a safety tread therefrom and to bond together such grains of desired antislipping characteristics by a ceramic material which is capable of uniting `intimately therewith and forming an integral, wearresisting tile body, in which the abrasive granules constitute the major portion of the tread volume and receive substantially all of the traffic wear.

A still further object is to provide a plane surfaced safety tile of simple design and of uniform appearance and composition, which may be manufactured in quantities and laid in position like ordinary flooring tiles to cover those areas which are most exposed to wear, without the necessity for supplementalV reinforcementsv appearing on `the tread surface.

With these and other objects in view as will appear from the following disclosure, my invention resides in the construction and the composition herein described and covered by the appending claims.

Referring to the drawings, in which like numerals indicate like parts:

Figure l is a perspective view fof one form of tile; and

Fig. 2 is a diagrammatic section of my tile embedded in concrete on the edge of a railroad platform.

ln the practice of my invention, l bond hard, anti-slipping and wear-resisting granular material into a desired shape by means of a bondino substance which yis durable and capable of holding the grains in place under all normal usages of pedestrian tranic and yet of breaking away ultimately to present fresh cutting grains on the surface when the old ones have become worn and dulled. Of the various hard materials suitable for safety treads which l may utilize, I find it desirable to employ those which have a hardness of 9 or more on Moliss scale, where traii'ic wear conditions are severe. As a specic example of such a wearresisting, anti-slipping material which is harder than 9, crystalline grains in which alumina is the main ingredient may be inentioned.

To prepare a tile of such hard granular material, l bond the grains toirether with a suitable substance capable or giving the block the desired tensile strength, toughness and wearing qualities. For this purpose l have found most satisfactory a ceramicv bond which may be vitriied or fused to a glassy condition around the granular particles and then solidilied into a magma tenaciously adhering to the grains and binding them together into a compact unitary mass. l preferably employ a vitriiiable glass rusing ceramic bond, such as a low fusing clay material, comprising for example feldspar mixed with slip clay and ball clay. Such a clay bond during its state of fusion ei'ects an exceedingly intimate union with the sur. face of the anti-slipping material. Where aluminum oXid'is the main ingredient of the hard granules, the fused clay material has a dissolving action upon 'the sur-face of the oxid grain, whereby the structure becomes substantially homogeneous and the grams are held firmly in place. t is orten found that the vitreous magma is iilled with sillimanite needles interlaced between the surfaces of the alumina crystals, this structure accountingl in part for the hardness and durability of the bond.

The tile may be made in accordance with approved ceramic methods. The nature or' the bond and the proportions of the ingredients depend upon the type and the sizes of the abrasive 1grains as well as the tiring and other operations employed, it being under- `stood that a ceramic article of this type consists Amainly of hard grains, and that the bond is contained largely in the voids bctween the grains but does not r'ill them; hence one ordinarily-employs only suiiicieut bond to give the desired physical Characteristics', with the dangers of swelling and of the bond strength being too weak as the usual limiting factors in determining the correctI proportions. As a specific example of one satisfactory composition made up ol feldspar, slip clay and ball clay to 'be treated as hereinafter described, l may' form a tile of 77% by weight of crystalline alumina grains and 23% of bond. These materials nase may be mixed in dry form; then after wetting the mixture suiiciently so that it will retain its shape, it is preferably subjected to high pressure in a steel mold of a desired form to make the mass dense and compact. Since the block in this condition has no strength or wearing qualities, it is rst dried and then red or burned in a suitable ceramic kiln, at a temperatur around 13000 C., depending upon the specie nature of the ingredients used, to produce a glassy condition in the bond. The burning is conducted slowly so as not to destroy the ware, the operation lasting, for example, l0() hours, after which the tile is cooled slowly for a similar length or time. By this means l produce a ceramic tile, unlilre a block of glass or porcelain containing hard grains embedded therein, but in which granular particles, 'comprising previously molten alumina, for example, are bonded by a glassy ceramic material into a dense, porous body, which in the speciic example given above, has a porosity of about 3G92 and a water absorption of about 15%. The alumina grains, which constitute the major portion or the body, are drawn together into av dense mass by the shrinkage of the ceramic material when fused. rlhis vitreous substance forms bonding' posts, as it were, between adjacent grainsuraces and leaves spaces interspersed therebetween, thus permitting a. large part of the grain surface to be exposed as well as providing sharp edged pores to assist in forming a safety tread.

illumina, to be suiiiciently hard for my purposes must be in a crystalline form. While the impure forms of crystalline aluminaA` such as emery and corundum which contain various proportions of other ingredients, may be utilized, l preferably employ an artificial substance prepared for example by melting alumina, bauxite, or other alumina containing material in an electric or other suitable type oi2 furnace. The molten mass may be allowed to cool and crystallize, whereby it becomes somewhat like corundum in its physical char. acteristics, especially with reference to its hardness. This material after crystallization or cooling,l is crushed and the resulting granules are graded, so that the proper sizes, as considered desirable, may be obtained for use.

Since the nou-slippingr characteristics or' the tread block will depend to some extent upon the size ot' the granules, l utilize that size of grain which is deemed the most suitable tor the particular location in which the block is to be placed. ViThile various sizes of grain may obviously be used, l prefer grains which will pass through a 60 mesh sieve oreven finer, smce this material will not have large destroying or abreding effects upon shoe leather and will be large enough to prevent slippine.

@wing to the ease with which this tile may be placed and held in position if laid in cement, l preferably so shape and construct the tile that it may be used in combination with a cement flooring. lere tofore, it has not been feasible to lay safety tread merely by embedding a bloeit of anti-slipping material in cement, so elaborate constructions have necessarily been pro'- vided to hold the tread in place.

Referring to Fig. l, l have there illustrated one form which a tile may be lgiven, this particular shape being adapted for a stair tread or a flooring edge, as on a platform near a car track. s illustrated, the tile is a flat plate l having e. continuous plane surface 2 for the tread, a rounded nose 3 on. the upper front corner vvherc Wear is most likely to occur, and a dovetail portion t having' beveled edges 5 at the rear to interlock with a concrete construction to hold the tile in place.. Other suitable shapes may obviously be employed to engage the cement or other means employed to hold the tile in place.

ln order to place this tile on a railroad platform, for example, l provide a cement foundation and embed a row of the safety blocks l at the forward edge of the Walking surface. The tile is sunk into the flooring or cement is placed in the rear thereof, so that the surface 2 of the tile is flush Wit-li and in the same plane with the cement surface Y of the platform. in this manner, l provide a smooth continuous plane for a tread surface, which will in no Way interfere with walkin or the Wheeling of trucks thereovcr, and wiich will resist Wear for a long period of time and remain uniform in its characteristics for preserving the safety of pedestrians.

l claim as my invention 1. An anti-slipping tread block compris ing anti-slipping particles of a hardness of 9 or more and a ceramic vitrified bonding;- material holding said particles together in a unitary wear resistingr structure, said particlcs constituting a major portion of the block and receiving substantially all of the traffic Wear.

2. An anti-slipping tread block comprisingl a body of Weanresisting, anti-slipping granules unitarily bonded by vitrifiable clay material fused into intimate Contact with the grains, said bond being hard, durable and capable of resisting;- the tendency for frictional Wear to strip said granules from the surface of the bloclr and disrupt its structure and said block having1 a high frictional coefficient permitting only a slight degrec of slippage and affording thereby an easy walmng tread surface.

slipping granular material of a hardness or '9 or more and a proportionately small amount of a vitrified, glassy ceramic bond imitarily united as a dense porous structure of high tensile strength, which has an imperforated and continuous tread portion consisting mainly of said granular material and bein(T capable of resisting Wear and preventing slipping of foot gear thereon.

6. in anti-slipping tile comprising Grains containing crystalline alumina bonded into a hard, Wear resisting body by a vitrifiable ceramic material fused into intimate contact with the grains, which is capable of resisting the normal abrading action of footwear tending to disrupt the bond, fracture the grain and dislodge particles thereof from the tile. Y

i'. i safety tile comprising crystalline leo alumina grains bonded by a vitrified, glassy ceramic material into a porous mass, said Lrains constituting the major portion of the A body and permanently forming an antislippingv tread surface under all conditions of Wear, and said bond uniting; integrally with the surfaces of alumina crystals.

8. i safety tread comprising a fiat plate of previously fused alumina grain bonded by a relatively small amount of a glass lio fused clay material, said plate being dense, hard, rough surfaced, Wear resistant and anti-slipping to footgear and having an imperforated, continuous, plane top surface consisting` substantially Wholly of alumina- H5 Lgrains which oifers no obstructions to traiic and may be easily cleaned and maintained in a sanitary condition.

9. An anti-slipping tile comprising small crystalline zgranules of hard, Wear-resisting 1Z0 material constituting; the major portion of the tile and a relatively small amount of bond containing,r a low fusing. clay material tired to a unitary mass.

l0. An anti-slipping'- tile comprising crys- 125 tallinc material of a hardness of 9 or more which Will pass through a 60 mesh sieve and a lovv fusing clay material containing slip clay fired to a glassy condition and bonding the crystalline material into a du- 13o rable mass, said crystaiine material consti- Ytilting the major portion of the iie surface and reveiving substantiaiy all of the Wear. 11. An anti-slipping tiie Comprising sma sized crystalline alumina. grains and a ceramic bond Containing a low fusing material fired to a dense vitreous mass and uniring separated grain surfaces, pores being interspersed with the bond masses between the grains and said alumina. consituting Jake major portion of the tread and receiving substantially all o the erafc weer.

remesa l2. An anti-siipping-ti1e comprising smal?. sized Crystalline alumina. vgranules and a lesser portion of a. glass-fused bond therefor 15 containing slip clay, edspar anc-1 bali day, said ie being dense, porous and having a tread surface consisting mainly of the alumine grannies.

Signed at New York, N. Y., this 25th day of April, i918.

HERBERT K. DODGE. 

